Investigation on Dynamic Changes in the Morphology and Fluorescence Properties of Sulfur Quantum Dots

Sulfur quantum dots (SQDs), an emerging metal-free quantum dot, which has received intense research interest owing to their unique optical property, good solubility, excellent biocompatibility, and facile synthetic approach. Herein, using sodium hypochlorite as the etching agent, we investigate how it functions and transforms sulfur powder to SQDs and affects the dynamics, photoluminescence, and size changes of SQDs by controlling the reaction time. Precise control of reaction time allows SQDs to be tuned between green and blue (from 515 to 420 nm) with size distribution ranging from 2.0 to 20 nm as well as the occurrence of a distinctive irregular rodlike structure. Surface functional groups and element analysis reveal that the core size and surface oxidizing sulfur species both contribute to the versatile PL properties. Morevoer, we propose a tentative formation mechanism that relies on the oxidizing sulfur surface state and quantum size effect, offering a theoretical and experimental foundation for investigation of we propose a tentative formation mechanism that relies on the oxidizing sulfur surface state and quantum size effect, offering a theoretical and experimental foundation for investigation of the formation and modulation of SQDs.